I bet you don't have very many education people tutoring calc though . . .unless your college is a lot different than mine was! It looks like the signs you're seeing for babysitting are for nanny type positions. You don't need anything that formal. Do you have any younger professors that like you? They might have a need for an occassional babysitter or have friends that do. If you go to church you could probably find people there too. You can make it through this position without credit cards . . .it will just take some creativity
Good luck!